Interpretive Summary: Variable rate fertilization (VRF) has a positive effect on the agricultural development and environmentally-friendly application of fertilizer. VRF is based on the crop productivity differences across a field and varying the inputs to a specific area of a field based on the nutrition or fertility in the soil. A VRF system was designed and manufactured, and prescription maps were developed based on nutrient levels and the yield goal. The VRF system increased maize yield by 11 to 33% and reduced application rates by 29 to 32% when compared to uniform application of fertilizer. Consequently, the VRF nearly doubled the cost-benefit ratio of the uniform application of fertilizer. The VRF system will provide a useful tool for farmers and researchers who want to apply precision agricultural technologies for enhanced crop production.

Technical Abstract:
The experiments of variable rate fertilization (VRF) for maize were carried out using a self-developed VRF system. In the studies, prescriptions of VRF were made for maize according to the nutrient levels in soil and the theory of yield goal. The results of this study have shown that VRF increased maize yield by 11% more in 2004 than that of conventional method of fertilization and 33% in 2005, and the application rate was reduced by 32% in 2004 and 29% in 2005. In addition to higher yields, VRF also increased the cost-benefit ratio under the condition of reasonable rate of fertilizer application.